Support sending passwords in cleartext

mason-postgres/src/connection.rs

@@ -78,6 +78,10 @@ impl Connection {
                     // there is no password needed
                 }
 
+                ServerMessage::AuthenticationCleartextPassword => {
+                    conn.send(PasswordMessage { password: options.password.unwrap_or_default() }).await?;
+                }
+
                 ServerMessage::AuthenticationMd5Password(body) => {
                     // Hash password|username
                     // FIXME: ConnectOptions should prepare a default user

mason-postgres/src/protocol/server.rs

@@ -76,6 +76,7 @@ impl Message {
 
             b'R' => match BigEndian::read_i32(&buf[idx..]) {
                 0 => Message::AuthenticationOk,
+                3 => Message::AuthenticationCleartextPassword,
                 5 => Message::AuthenticationMd5Password(AuthenticationMd5Password {
                     salt: buf.slice_from(idx + 4),
                 }),